The chief objectives of this work are to determine mechanisms by which electronic excitation can be degraded, stored and transferred in large molecules and molecular complexes; to determine the role that the environment plays in these processes; and to determine mechanisms and paths followed in electron transfer processes. Our approach is to use the techniques of molecular photochemistry, spectroscopy and electrochemistry to study in relatively simple or at least well-defined systems. These phenomena, which have close analogies with processes involved in vision, photodynamic deactivation, biological electron transfer and photosynthesis. The proposed investigations include studies of the photoreactions of metalloporphyrin complexes in solution, films and monolayer assemblies, investigation of electron transfer processes with metalloporphyrins and related metal complexes and spectroscopic and photochemical studies of olefins, dienes and polyenes in monolayer assemblies. (keywords for the latter area; photoreactions of oriented molecules and complexes).